After Google announced on Tuesday that it was integrating material from Google Plus into its search results, the Web shot back, accusing the company of pushing aside competing social networks like Twitter and Facebook.

Of course, these Google Plus results will stand higher on the page than information from other social networks. Searching someone’s name, for example, will put that person’s Google Plus page directly at the top of the Google search box.

James Grimmelmann, an associate professor at New York Law School who specializes in Internet law, wrote on Twitter, “Today is a good day to turn off Google+ and delete your Google Profile. I just did.”

“I don’t like it. I don’t like it for its effect on competition, and I don’t like it for what it does to people’s privacy,” Mr. Grimmelmann added in a phone interview. “It breaks down a very clear conceptual divide between things that are private and things that are public online.” He added that many Google users would find the integration confusing, and that the updates would lead to a “sense of erosion of their privacy.”

Google could argue that Facebook does not make its updates public to search engines, so Google cannot highlight this content in search results. But Twitter does. All Twitter messages are public, unless a person designates an account as private, and they are accessible to any search engine.

Facebook and Google did not respond to a request for comment. Twitter issued a statement saying that the change could be bad for users and others:

For years, people have relied on Google to deliver the most relevant results anytime they wanted to find something on the Internet. Often, they want to know more about world events and breaking news. Twitter has emerged as a vital source of this real-time information, with more than 100 million users sending 250 million Tweets every day on virtually every topic. As we’ve seen time and time again, news breaks first on Twitter; as a result, Twitter accounts and Tweets are often the most relevant results. We’re concerned that as a result of Google’s changes, finding this information will be much harder for everyone. We think that’s bad for people, publishers, news organizations and Twitter users.

Alex Macgillivray, Twitter’s general counsel on policy, trust and safety, said on his company’s service that this was a “bad day for the Internet.” Mr. Macgillivray, who once worked as a lawyer for Google, said he could imagine the opposition within the company to “search being warped this way.”

Mark A. Lemley, a professor at Stanford Law School who directs the program in law, science and technology, said in a phone interview: “There is a lot of concern on various fronts about Google favoring Google in its own search results, and I think this will add to that concern.” Mr. Lemley has worked with Google in the past on unrelated legal matters.

Professor Lemley said that the move should not be viewed in anticompetitive terms. “It can’t be the rule that if Facebook says no, you can’t search our links, that Google can’t search its own links. That is not antitrust.”

Mr. Grimmelmann of New York Law School added: ”In Google’s own interest, they should continue to focus on building a really great search platform, and not trying to prop up a not very great social network by roping it to a search engine.”